I would take a second look and make sure the starter is bad before proceeding with its R&R. Are battery and ground strap connections OK? Is your remote starter switch OK and was it making a good connection? Are the connections and wiring to the starter OK? Maybe the starter just needs to be cranked a bit since it sat for 5 years and some corrosion set in?

Removing/ installing a starter in a 617 turbo is not a fun job. Make sure you have a plan B if plan A (jack stands + long 1/2" extensions) don't work out.
I tried plan A on my 83 but only had 3/8" drive long extensions. Problem I ran into was I didn't have enough swing room with the long pipe (for leverage) on the 1/2 " breaker bar and 1/2" ratchet that I used because my jack stands was not tall enough (leverage pipe was hitting the ground due to the 3/8" drive long extensions twisting and I was not able to break loose the upper starter bolt). I did not want to buy 1/2" drive long extensions not knowing if it would make a difference so went to plan B and got the job done.

If you strip the upper Allen starter bolt, engine has to come out.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked